1. Field of the Invention
This invention relates to electromagnetic anisotropic devices and particularly to such devices made out of a current conductive rod which is carrying sufficient current therethrough to reverse the direction of the helical magnetization produced by said current each half cycle. More particularly, this invention relates to such electromagnetic anisotropic devices that have a conductive coil wound around the current carrying rod for producing an output voltage in accordance with the change in axial flux linkages resulting from the change in direction of helical magnetization.
2. Description of the Prior Art
For many years the so-called Wiedemann Effect has been well known. The Wiedemann Effect is the twist produced in a wire that exhibits magnetostriction when that wire is placed in a longitudinal magnetic field and an electric current flows through the wire. The converse or inverse of this phenomenon has also been recognized and is commonly called the Inverse Wiedemann Effect. In the Inverse Wiedemann Effect, axial magnetization is produced in a magnetostrictive wire that carries currrent therethrough when the wire is being twisted.
There have been a number of attemps to employ the Wiedemann and Inverse Wiedemann Effect in practical applications. Such attempts are discussed at length in an article by J. A. Granath entitled "Instrumentation Applications Of Inverse Wiedemann Effect" which appeared in the Journal of Applied Physics, Volume 31, pp 178S-180S (May 1961), and in a publication by the International Nickel Company, Inc. of New York, N.Y., entitled "Magnetostriction". At least two U.S. patents disclose the devices relied upon in the Inverse Wiedemann Effect, namely U.S. Pat. No. 2,511,178 granted to H. C. Roters on June 13, 1950, and U.S. Pat. No. 3,083,353, granted to A. H. Bobeck on Mar. 26, 1963. The Roters patent is directed to devices including magnetostrictive rods that exhibit essentially a linear characteristic curve when one plots the axial magnetic induction (B.sub.ax) versus the angle of twist (.alpha.) of said rod. There is no suggestion in Roters of using anisotropic materials. Bobeck, on the other hand, does rely on anisotropy for producing a memory device for computers or the like. However, in the Bobeck devices the level of the current being passed through the anistropic rod is never sufficient to cause a reversal of the direction of helical magnetization in said rod and hence is insufficient to cause a change in flux linkage with the surrounding coil to produce an output voltage.